Self-locking ladder for floating roof tanks



Jan. 21, 1930. c. s. MORGAN ET AL 1,744,239

SELF LOCKING LADDER FOR FLOATING ROOF TANKS Filed Jan: 1929 3 y Q k519 2 INVEN TORS (ZarZeJ Sfforyazz i Jafin Tflowell A TTORNEY.

Patented Jan. 21, 1930 UNITED STATES PATENT ()FFICE CHARLES S. MORGAN AND JOHN T. HOV/ELL, OF 1305 ANGELES, CALIFORNIA, ASSEGNORS TO UNION OIL COMPANY OF CALTFOBLHIA, CI? LOS ANGELES, CALIFORNIA, A COR- PORATION OF CALIFORNIA.

SELF-LOCKING LADDER FOR FLOATING ROOF TANKS Application filed January 9, 1929.

This invention relates to ladders and has been developed especially for use upon floating root tanks which rise and tall with the liquid level, such type of tanks being in common use in the petroleum industry.

The object of this invention is to present a ladder construction of the character stated which will provide for the securing of the lower end of the ladder to a tank root, for running the ladder into and out or the tank as the root rises and falls in such manner that the surplus portion of the ladder may depend outside of the tank and be drawn back into the tank when the liquid level drops, for maintaining the service portion of the ladder (that part within the tank) rigid for use, and for automatically controlling the movement of all parts. It is also an object of the invention to provide a ladder of the type described which shall contain a minimum of parts and require minimum attention for maintenance.

Briefly stated, the invention comprises a plurality of flexibly connected sections, each of which sections is rigid in itself and includes a rung or tread and means for releasably lOCkillg adjacent sections in order that the useful portion oi: the ladder within the tank will be always rigid, and the surplus portions of the ladder may pass over the edge of the tank to the outside as the roof rises and may be drawn back into the tank as the root falls. The invention also comprises a re leasably locked sectional structure as above described in combination with a cooperating device, across which the surplus portion of the ladder passes having means for operating the releasablelocking device. In a preterred embodiment, the cooperating means is in the form of a drum having annular ledges which the ladder sections engage and over which they pass and bevelled portions for engage ment by and operation of the releasable means. Or more broadly stated, the invention comprises a flexible ladder whose lower end is adapted to be secured to a floating root and having a plurality of rigid sections fleX- ibly connected and provided with means for releasably locking certain sections into a rigid Serial No. 331,186.

portion in combination with means for automatically operating the locking means.

In the accompanying drawings wherein one desirable form of the invention is illustrated,

Fig. 1 is a side elevation of the ladder mounted in operative position upon a tank having a floating roof;

F 2 is a front elevation showing particularly the service portion of the ladder disposed within the tank;

Fig. 3 is an elevational detail showing a joint and its locking means viewed from the side of the ladder as indicated by the line 33 of Fig. 2;

Fig. elis a View taken at right angles there to from the line of Fig. 3;

Fig. 5 1s a cross sectional detail taken on on the line 5-5 of Fig. 1 and indicating how the locking means is released by the drum over which the ladder sections roll;

Fig. 6 is a cross sectional detail taken on the line 6--6 of Fig. 4:;

Fig. 7 is an elevational detail, and Fig. 8 is a cross sectional detail taken on line 8-8 of Fig. 7, these two figures indicating latch movement for return of sections to alignment.

In these drawings a ladder constructed according to the present invention is shown as mounted upon a petroleum storage tank 10 and its floating root 12, said root having secured thereto a pair of brackets 1a to which the lowermost section of the ladder is pivotally connected as at 15. The outer edge of the tank wall 10 carries a framework generally indicated at 16 and suitably braced, this framework conveniently comprising a platform 17 accessible by means of an ordinary steel ladder 18, and carrying journals 19 for the shaft 20 of a reel or drum 21 over which the surplus portion of the ladder passes.

The ladder proper comprises a plurality of sections each of which is generally indicated at 22 and comprises a pair of oppositely disposed links or spacers 23 between the upper ends of which a tread or rung 241 extends and to which upper ends said link is secured as best seen in Fig. 1. The lower ends of each pair of links 23 are offset inwardly as indicated at 25 to form offset portions 23 in order that said lower ends may lie within and alongside of the upper ends of the adjacent links 23, the treads 24 passing through said offset lower ends just below the offsets 25 and acting as bearings about which the respective links pivot. In order that said offset lower ends may be prevented from moving inward from aligned position, collars 26 are fixed upon the treads 2-1 to retain said offset link ends against inward movement. The forward edges of the links 23 as "iewed in F 2 and 4 are provided with laterally offset and reversely turned retaining lugs 28 which serve to engage the lower extremities of the offset link portions when adjacent sections are in properly aligned or operative position to insure against doubling back beyond dead center. Thus the treads or rungs 24 serve to properly space the opposite links of each section and also to pivotally connect adjacent sections with each other.

In order that adjacent sections may be locked in longitudinal alignment to form a rigid operative ladder length, a locking device is provided at each joint, this device being in the form of a latch 30 mounted upon a spring arm 31 secured to the offset portion 23 of each link as indicated at 32. The latch 30 normally is received in apertures or pocket. 33 formed in the adjacent portions of the links 23 and their oflset portions 23, Figs. 3 and 5, thereby locking adjacent links against swinging motion about rungs 24.

The various spring arms 31 when in normal position are vertically aligned as indicated in Fig. 1 in order that they may be successively operated as the ladder sections pass over the drum 21. The peripheral portions of the heads of the drum 21 serve as annular flanges to position the links 23, and these links are adapted to engage and roll over horizontally disposed annular tracks 35 formed in the drum barrel 21' said drum barrel also be ing offset to provide annularly disposed bevelled walls 36 which are engageable by the ex" tremities of the spring fingers 31 to withdraw the latches 30 from the recesses 33 as said links 23 roll over their annular tracks 35.

In operation, a number of the lower ladder sections 22 are usually vertically aligned with the latches 30 in locking position to form a rigid serviceable ladder length upon which an attendant may descend to the tank roof for inspection. As the tank roof rises upon elevation of the li uid level, the ends of the respective spring fingers 31 engage with the bevelled annular walls 36 of the drum barrel 21, thus withdrawing the latches 30 from the respective apertures 33 to permit the joints to break so that the ladder section next above will swing about run 24 as seen at the left of the Fig. 1. This permits the surplus portion of the ladder to roll over the drum 21 into vertical position outside of the tank, a counterweight VV being provided to insure proper movement. Incidently the surplus portion outside of the tank also is locked in rigid position by the latches 30 and when the tank roof descends, these latches will be withdrawn to permit return of the ladder sections as just described.

At certain stages of the passage of the links over the drum 21, the ofl'set ends 23 are moved outside of the range of the adjacent link portions 23 as indicated at the top of Fig. 1, so that the spring fingers 31 disengage the bevelled walls 36 and permit the latches 30 to re-enter the respective aperture 33. As these sections begin to approach alignment and. before the extremities of the spring fingers 31 come into engagement with the bevelled walls 36, the respective latches 30 come into engagement with the outer edges of the adjacent links 23, and in order to withdraw each latch 30 it is necessary that the adjacent face of: the outer portion thereof be bevelled as at 30 so that it will ride over the edge of the adjacent link 23 and thereby shift the latch.

From the foregoing it will be clear that depending portions of the ladder are locked in rigid relation with the sections properly aligned and that as the surplus portions pass over the drum 21 the latches will be properly released to permit such passage.

Vhile we have disclosed one desirable embodiment of the invention, it is to be understood that this torm is presented merely as an illustration, and is not to be considered as limiting the generic invention, since many modifications within the scope of the claims will be obvious to those skilled in the art.

e claim:

1. A ladder comprising a plurality of swingingly connected ri id sections, means carried by the sections tor locking adjacent sections in alignment to form a rigid ladder portion, certain sections having treads, and means disposed adjacent said ladder and into engagement with which said ladder sections are adapted to be moved for automatic release or said locking means.

2. A ladder for floating roof tanks and the like comprising a plurality of hingedly con nected rigid sections, means for locking adjacent sections in rigid relation when in longitudinal alignment, means over which said ladder sections are adapted to move, said sections being adapted to swing on said hinge connections in their movement over the last mentioned means, and means adjacent said last mentioned means for automatically releasing the locking means for such swinging movement.

3. A ladder -for floating root tanks and the like comprising a plurality of flexibly connected rigid sections, means for locking adj acent sections in rigid relation when in longitudinal alignment, means to receive said ladder sections for movement of said sections therearound, and means cooperating with the receiving means to automatically release said locking means to permit relative travel of the sections about said receiving means.

4. A construction according to claim 1 wherein each locking means comprises a latch movable into apertures in the respective ladder sections, movable means carrying said latch and actuable by the releasing means, one face of such latch being bevelled to permit return of one section into alignment with an adjacent section, another face of said latch being perpendicular to the direction of swing to prevent swing in one direction and a retaining lug on one section to prevent swing in the opposite direction.

5. A construction according to claim 3 wherein a counter-weight is secured to that end of the ladder which passes over and depends from the receiving means.

6. A ladder for floating roof tanks and the like comprising a plurality of hingedly connected rigid sections having treads, means for locking adjacent sections in rigid relation when properly aligned, a drum having tracks over which upper sections are adapted to travel to depend on the other side thereof, a means working in cooperation with the tracks on said drum for releasing the locking means on sections approaching the drum to permit the surplus sections to roll thereover.

7. A collapsible ladder comprising a plurality of flexibly connected rigid sections, means for locking said sections in aligned position, means located at a predetermined point and with relation to which means said ladder sections are movable, the last named means cooperating with the ladder sections for automatically releasing respective locking means to collapse respective ladder sections as they pass said point.

8. In combination a tank, a floating roof therein, a ladder secured to said roof and comprising a plurality of hingedly connected sections extending upward therefrom, means for releasably locking said sections in vertical alignment, and means at the top of the tank for releasing the respective locking means to collapse respective sections as they pass the top of the tank.

9. A ladder comprising a plurality of flexibly connected rigid sections, each section including' a tread, means for locking said sections in alined position, means cooperating with said locking means to automatically re lease said locking means, said locking means comprising a latch adapted to enter pockets in adjacent sections, an arm upon which said latch is carried and by movement of which said latch is withdrawn.

In witness whereof we a'liix our signatures.

CHARLES S. MGRGAN. JOHN T. I-IOWVELL. 

